1. Field of the Invention
The present invention generally relates to an improvement of a cathode ray tube apparatus having a cathode ray tube and a magnetic deflection means, and especially to a cathode ray tube apparatus for producing rectangle raster of very small distortion.
2. Description of the Prior Art
There are many kinds of deflection means to be applied for a cathode ray tube to deflect its electron beam; in a cathode ray tube apparatus using deflection means to form uniform magnetic field has a shortcoming that, though it has small deflection distortion, its raster is liable to have shape distortion, and thereby, raster distortion compensation permanent magnets are required. On the other hand, in another cathode ray tube apparatus using deflection means which forms deflection magnetic field of pin-cushion distribution of magnetic flux, though the apparatus can project accurately rectangle shaped raster without use of the compensation magnets, the apparatus has a large deflection distortion, and especially at the peripheral parts of the phosphor screen the electron beam spots are liable to have shape distortion, thereby making attainment of high resolution difficult.